Run results for: querySelector vs getElementsByTagName simple select

Run details:

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:139.0) Gecko/20100101 Firefox/139.0

Browser: Firefox 139

Operating system: Windows

Device Platform: Desktop

Date tested: 6 months ago

getElementsByTagName for none existing element

12.8M/s

getElementsByTagName for existing element

12.6M/s

querySelector for existing element

6.6M/s

querySelector for none existing element

6.6M/s

View exact numbers

Test name	Executions per second
✓ getElementsByTagName for none existing element	12,766,940 Ops/sec
getElementsByTagName for existing element	12,592,863 Ops/sec
querySelector for existing element	6,634,838 Ops/sec
querySelector for none existing element	6,621,586 Ops/sec

HTML Preparation code:

<div>
  <test><test2></test2></test>
  <test><test2><test3></test3></test2></test>
  <test></test>
</div>

Tests:

querySelector for existing element
const found = document.querySelector('div');
getElementsByTagName for existing element
const found = document.getElementsByTagName('div');
querySelector for none existing element
const found = document.querySelector('span');
getElementsByTagName for none existing element
const found = document.getElementsByTagName('span');